Yield performance and agronomic characteristics of a newly developed ultrashort-duration line in direct-seeded double-season rice system

: The objective of this study is to explore the yield performance and yield-related traits of a newly developed ul-trashort-duration line in direct-seeded double-season rice system. An ultrashort-duration line named CPPC18, and four check cultivars (Xiangzaoxian 6, Zaoxian 615, Zhongzao 39, and Liangyou 152) were grown as the direct-seeded double-season rice in both plot-level and on-farm experiments in Hubei province in 2021. We measured canopy light interception, biomass accumulation, lodging characteristics, yield, and yield components. The result showed that the new line matured within 95 days in each season, and its annual growth duration was 180–183 days. This was 7–9 days longer than Xiangzaoxian 6, but 4–8 days and 16–22 days shorter than Zaoxian 615 and the combination of Zhongzao 39 (early season) and Liangyou 152 (late season), respectively. In